1. Field of the Invention
This invention relates to a variable ratio chain sprocket wherein the torque transmission ratio is controlled by the torque applied to the sprocket. The ratio is changed by varying the effective diameter of the sprocket, while providing means for keeping the chain in mesh with the sprocket as the diameter is varied.
2. Description of the Prior Art
Power transmission systems having pulleys with infinitely variable diameters are well known, as illustrated by the following issued U.S. Pat. Nos.:
672,962 Seymour 1,496,032 Sleeper 1,626,701 Sleeper 3,279,271 Sockl
All of these patents show such an infinitely variable pulley associated with a belt drive power transmission system. The concepts of these prior art power transmission systems have not been utilized in a chain drive sprocket due the impossiblility of maintaining the chain engaging sprocket teeth in constant mesh with the chain, since the circumferential distance between the teeth varies as the diameter of the sprocket varies.
U.S. Pat. No. 2,421,368 to Aubert discloses a chain sprocket having a variable diameter to change the drive ratio, but the diameter is adjustable only to finite positions in order to insure that the sprocket teeth are properly spaced to engage the chain. Thus, an infinitely variable power transmission ratio is impossible utilizing the Aubert apparatus.
U.S. Pat. No. 1,633,746 to Jereczek discloses a chain drive sprocket having adjustable teeth to maintain engagement with the chain despite stretching or wear in the chain. However, there is no adjustable diameter shown by Jereczek to vary the power transmission ratio. Indeed, due to its complexity, it would be impossible to utilize the Jereczek apparatus in conjunction with a variable diameter, chain drive sprocket.
It is an object of the instant invention to provide a chain drive sprocket having an infinitely variable power transmission ratio.
It is a further object of the invention to provide a chain drive sprocket wherein the power transmission ratio varies with the torque applied to the sprocket.
Additionally, it is an object of the invention to provide a chain drive sprocket having means to insure that at least one tooth is in mesh with the chain regardless of the diameter of the chain sprocket.